5916 research outputs found
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Seismic performance assessment of an existing anchored and a self-anchored liquid storage tank in high seismic regions
No full textThis study presents seismic performance of two existing at-grade industrial liquid-storage tanks located in the Eastern part of Marmara region, which is a high seismic region in Turkey. The first tank is self-anchored (unanchored) and has been in service for 44 years, while the other tank is mechanically anchored to a reinforced concrete foundation and has been in service for 50 years. Tanks seismic performance is evaluated using tank time-history earthquake analyses with recorded ground motions scaled for each tank site. The liquid content was included in the developed model using provisions of API 650. Tanks base uplift, sliding on the foundation, tank shell and bottom plate damage, and demand on tank anchorage were determined. The results shows that self-anchored tank has base plate uplift and sliding that are larger than the allowable limits while the mechanically anchored tank has acceptable seismic performance with potential seismic damage of tank anchorage system. The findings of this study contribute valuable insight into the seismic performance of existing liquid storage tanks in the region under new seismic regulations and increased seismic loads than those used for their design.TÜBİTAKPublisher versio
A new approach to local resource sharing systems: Document Supply Tracking System (KİTS) modal proposal
No full textAnatolian University Libraries Consortium (ANKOS) was established in 1999 to enhance the support of libraries to education and research by realizing the highest level of access of academic libraries in Türkiye to the global information network (ANKOS, 2024). Under the consortium’s umbrella, the "Collaboration Research Group" was formed in 2006 for resource sharing and this group implemented Document Supply Tracking System (KİTS) project. KİTS is an online platform aimed at tracking resource sharing activities carried out in university libraries and information centers. This system, which is completely free and online, is used by ANKOS member higher education institutions (KİTS, 2006)
İnsan yönlendirmeli paylaşımlı kontrol ile robot öğrenimini hızlandırma.
No full textThis thesis presents a training procedure for reinforcement learning-based robot control to achieve skill acquisition with reduced training time and data requirements. It achieves this by actively incorporating the actions provided via human inputs in addition to actions generated by the learning algorithm. As the algorithm acquires the target skill, the contribution of the human actions is gradually decreased for autonomous task execution. To demonstrate the efficacy of the proposed approach, a ball-balancing task with manipulability index maximization was chosen. In this task, a 7-DoF robot arm achieved skill acquisition via reinforcement learning in which two distinct training approaches were employed: i)autonomous training, and ii) human-in-the-loop training approach. The task required the robot to bring the ball to the center of a tray attached to its end-effector, starting from arbitrary initial ball positions in the face of perturbations. Simulation experiments were carried out with 24 human participants where each participant guided robot learning in a human-in-the-loop shared control setting. Compared to autonomous training, the human-in-the-loop training approach showed superior performance in terms of reduced training time and data usage while exhibiting favorable ball-balancing skills.Bu tez, eğitim süresini düşürerek ve veri gereksinimlerini azaltarak insandan robota beceri kazanmayı amaçlayan öğrenmeye dayalı robot kontrolü için bir eğitim süreci sunmaktadır. Bu eğitim prosedürü, öğrenme algoritması tarafından üretilen komutlara ek olarak, insanın döngüye katılmasıyla sağlanan komutları etkin bir şekilde kullanarak eğitim sürecinin hızlanmasını sağlar. Algoritma hedef beceriyi kazandıkça insan eylemlerinin katkısı, görevin otonom gerçekleştirilebilmesi için kademeli olarak azaltılmıştır. Önerilen yaklaşımın etkisini gözlemlemek için, manipulabilite indeksinin iyileştirilmesi gözetilerek robotun uç işlevcisinde top dengeleme görevi seçilmiştir. Bu görevde, 7 serbestlik dereceli bir robot kolun öğrenme yoluyla beceri kazanmasını sağlamak için iki farklı eğitim yaklaşımı kullanılmıştır: i)otonom eğitim, ve ii) insanın eğitim döngüsüne dahil olduğu yaklaşım. Görev, robotun topu, rastgele belirlenmemiş pozisyonlarından başlayarak, robotun uç işlevcisine bağlı bir tepside dengelemesini gerektirmektedir. Otonom eğitime benzer şekilde, önerilen yaklaşım için 24 katılımcı ile benzetim çalışmaları gerçekleştirilmiştir. Her bir katılımcı robotu, insanın dahil olduğu paylaşımlı kontrol ortamında yönlendirmiştir. Otonom eğitimle karşılaştırıldığında, insanın dahil olduğu eğitim yaklaşımı, eğitim süresinin ve veri kullanımının düşürülmesini sağlayacak şekilde olumlu bir performans göstermiş ve top dengeleme becerisini başarılı bir şekilde sergilemiştir
High-power 120 fs pulses at 1.23 GHz from a single-mode Er/Yb-doped fiber laser
No full textWe present a compact single-mode erbium-doped master oscillator power amplifier (MOPA) fiber laser that can directly produce 100 fs pulses at 2.2 Wand 120 fs pulses at 4.5 W average power. The laser operates at 1.2 GHz pulse repetition rate, with a central wavelength at around 1550 nm. The laser system consists of a passively mode-locked oscillator with a repetition rate of 77.6 MHz and an average power of 16.3 mW. Using a repetition rate multiplier consisting of five 50/50 couplers, we achieved pulses with a repetition rate of 1.23 GHz. The output was increased to an approximately 4.5 W average, corresponding to about 3.6 nJ pulse energy using only one amplifier stage comprising a cladding pump 10/125 erbium-ytterbium (Er/Yb) co-doped gain fiber. We characterized the system by measuring the optical spectrum and intensity autocorrelation at different output powers, 1.5 W, 2 W, 2.2 W, 3 W, 4 W, and 4.5 W. Finally, we used numerical simulations to study the pulse and optical spectrum evolutions in the fiber, and investigated the output pulse and spectrum at different output powers. We achieved a very good agreement with experimental results, inferring the pulse dynamics and its power scaling limitations. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.Yüksekoğretim Kurulu ; TÜBİTA
Operation altitude optimization of airborne FSO links in the presence of pointing errors
No full textWith its ultra-high capacity, free space optical (FSO) communication is an ideal backhaul solution for non-terrestrial networks (NTNs). Unlike traditional terrestrial FSO systems, airborne FSO terminals are subject to significant pointing errors. In particular, the rotational stability of a rotary-wing UAV arises from rolling, yawing, and pitching and induces altitude-dependent shifts in the center of the received beam. This motivates the optimal selection of operation altitude to minimize the effects of pointing errors. In this paper, we analyze the bit error rate (BER) of a UAV-mounted FSO link in the presence of pointing errors and determine optimal operation altitudes to minimize the BER.TÜBİTA
Study of azimuthal anisotropy of Υ(1S) mesons in pPb collisions at √ NN = 8.16TeV
No full textThe azimuthal anisotropy of [Formula presented] mesons in high-multiplicity proton-lead collisions is studied using data collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 8.16TeV. The [Formula presented] mesons are reconstructed using their dimuon decay channel. The anisotropy is characterized by the second Fourier harmonic coefficients, found using a two-particle correlation technique, in which the [Formula presented] mesons are correlated with charged hadrons. A large pseudorapidity gap is used to suppress short-range correlations. Nonflow contamination from the dijet background is removed using a low-multiplicity subtraction method, and the results are presented as a function of [Formula presented] transverse momentum. The azimuthal anisotropies are smaller than those found for charmonia in proton-lead collisions at the same collision energy, but are consistent with values found for [Formula presented] mesons in lead-lead interactions at a nucleon-nucleon center-of-mass energy of 5.02 TeV.SC (Armenia), BMBWF and FWF (Austria); FNRS and FWO (Belgium); CNPq,
CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES and BNSF (Bulgaria); CERN; CAS, MOST, and NSFC (China); Minciencias (Colombia); MSES and CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER, ERC PUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); SRNSF (Georgia); BMBF, DFG, and HGF (Germany); GSRI (Greece); NKFIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MES and
NSC (Poland); FCT (Portugal); MESTD (Serbia); MCIN/AEI and PCTI (Spain); MoSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); MHESI and NSTDA (Thailand); TUBITAK and TENMAK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).
Individuals have received support from the Marie-Curie programme
and the European Research Council and Horizon 2020 Grant, contract
Nos. 675440, 724704, 752730, 758316, 765710, 824093, and COST
Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the
Science Committee, project no. 22rl-037 (Armenia); the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche
dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap
voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the
F.R.S.-FNRS and FWO (Belgium) under the “Excellence of Science –
EOS” – be.h project n. 30820817; the Beijing Municipal Science &
Technology Commission, No. Z191100007219010 and Fundamental
Research Funds for the Central Universities (China); The Ministry of
Education, Youth and Sports (MEYS) of the Czech Republic; the Shota
Rustaveli National Science Foundation, grant FR-22-985 (Georgia); the
Deutsche Forschungsgemeinschaft (DFG), under Germany’s Excellence
Strategy – EXC 2121 “Quantum Universe” – 390833306, and under
project number 400140256 - GRK2497; the Hellenic Foundation for
Research and Innovation (HFRI), Project Number 2288 (Greece); the
Hungarian Academy of Sciences, the New National Excellence Program
- ÚNKP, the NKFIH research grants K 124845, K 124850, K 128713,
K 128786, K 129058, K 131991, K 133046, K 138136, K 143460,
K 143477, 2020-2.2.1-ED-2021-00181, and TKP2021-NKTA-64 (Hungary); the Council of Science and Industrial Research, India; ICSC – National Research Centre for High Performance Computing, Big Data and
Quantum Computing, funded by the EU NexGeneration program (Italy);
the Latvian Council of Science; the Ministry of Education and Science,
project no. 2022/WK/14, and the National Science Center, contracts
Opus 2021/41/B/ST2/01369 and 2021/43/B/ST2/01552 (Poland); the
Fundação para a Ciência e a Tecnologia, grant CEECIND/01334/2018
(Portugal); the National Priorities Research Program by Qatar National
Research Fund; MCIN/AEI/10.13039/501100011033, ERDF “a way of
making Europe”, and the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant
MDM-2017-0765 and Programa Severo Ochoa del Principado de Asturias (Spain); the Chulalongkorn Academic into Its 2nd Century Project
Advancement Project, and the National Science, Research and Innovation Fund via the Program Management Unit for Human Resources &
Institutional Development, Research and Innovation, grant B05F650021
(Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the
Weston Havens Foundation (USA
Cam tavlama fırınlarında soğutma bölgesinin sayısal olarak incelenmesi.
No full textAnnealing, a crucial heat treatment process in the glass manufacturing industry, aims to alleviate the residual thermal stresses induced during the rapid cooling of glass following the forming stage. In the production of container glass, continuous annealing furnaces are employed for this process, consisting of distinct zones tailored to meet specific process requirements. The initial segment of the furnace, the upstream heating zone, is responsible for raising the glassware's temperature to the annealing point. After the heating zone, multiple cooling zones gradually lower the temperature of the glass objects under precise control. To enhance convective cooling rates and ensure uniform air temperatures within the furnace, circulation fans are typically installed in the cooling zones. This study focuses on numerically investigating the influence of circulation airflow rates, namely 0.6(m^3)s, 0.8(m^3)s, and 1(m^3)s, on the cooling performance within an industrial-scale continuous container glass annealing furnace. Two separate solvers are employed in an iterative approach. One solver addresses transient heat conduction within the glass bottles, utilizing radiative and convective heat fluxes as boundary conditions. The other solver is focused on solving the steady convection pattern inside the furnace. Results showed that increasing the circulation fan flow rate enhances the convective heat transfer inside the zone and increases the cooling rate of moving glass bottles. Moreover, increasing the fan flow rate also resulted in a more uniform cooling behavior in glass indicating a reduction in the residual thermal stress levels.Cam üretim endüstrisinde önemli bir ısıl işlem süreci olan tavlama, camın şekillendirme aşamasını takiben hızlı soğutma sürecinden kaynaklanan kalıntı termal gerilmeleri hafifletmeyi amaçlar. Konteyner cam üretiminde, bu süreç için sürekli tavlama fırınları kullanılır ve belirli işlem gereksinimlerini karşılamak üzere uyarlanmış farklı bölgelerden oluşur. Fırının ilk bölümü olan ısıtma bölgesi, cam eşyaların sıcaklığını tavlama noktasına çıkarmaktan sorumludur. Isıtma bölgesinden sonra, birden fazla soğutma bölgesi, cam nesnelerinin sıcaklığını hassas kontrol altında aşamalı olarak düşürür. Fırın içinde konvektif soğutma hızlarını artırmak ve fırın içinde homojen hava sıcaklıklarını sağlamak için genellikle soğutma bölgelerine dolaşım fanları yerleştirilir. Bu çalışma, endüstriyel ölçekte bir sürekli konteyner cam tavlama fırını içinde dolaşım fanlarının hava akış hızlarının,bu projede kullanılan akış hızları 0.6(m^3)s, 0.8(m^3)s, ve 1(m^3)s, soğutma performansına olan etkisini sayısal olarak incelemektedir. İki ayrı çözücü, iteratif bir yaklaşım içinde kullanılmaktadır. Bir çözücü, cam şişeler içinde zamana bağlı ısı iletimini ele alır ve sınırlama koşulları olarak ışıma ve konvektif ısı akılarını kullanır. Diğer çözücü ise fırın içindeki kararlı haldeki konveksiyon dağılımını çözmeye odaklanmıştır. Sonuçlar, fanın akış hızının artırılmasının bölge içinde konvektif ısı transferini artırdığını ve hareket eden cam şişelerinin soğuma hızını artırdığını göstermiştir. Ayrıca, fan akış hızını artırmanın camda daha homojen bir soğuma davranışına yol açtığı göstermiştir
Offline reinforcement learning for bandwidth estimation in rtc using a fast actor and not-so-furious critic
No full textThe increasing demand for real-time communication (RTC) applications necessitates robust and reliable systems. Seamless media delivery depends on an accurate assessment of the network conditions, with bandwidth estimation (BWE) being crucial for maintaining system reliability and achieving good quality of experience (QoE) for the users. BWE poses a significant challenge due to dynamic network conditions, limited information availability and computational complexity. The Second Bandwidth Estimation Challenge, organized within ACM MMSys 2024, aims to enhance RTC user QoE by developing a deep learning-based bandwidth estimator using offline reinforcement learning. This paper presents our solution, ranked second in the grand challenge. This solution employs an actor-critic approach to achieve accurate real-time BWE by relying solely on observed network statistics. Due to the offline setting of the challenge, the critic network is trained separately from the actor network to estimate the action quality without interacting with the real environment. Furthermore, the quality prediction by the critic is adjusted by a predefined conservation factor to address overshooting the bandwidth values. The solution's source code is publicly available at https://github.com/streaminguniversity/FARC
Competitive dynamic pricing under capacity constraints: An experimental study
No full textKeeping up with competitors' prices is one of the top operational challenges in pricing. However, competitive interactions in revenue management have not received much research attention in the past due to their complexity. We conduct a series of laboratory experiments to investigate the dynamic pricing behavior of two capacity-constrained firms under competition. Our experiments initially control for strategic interactions between the sellers and then allow for them. To gain a broader understanding, we also manipulate demand uncertainty and the expected market size. Our results confirm the dependency of dynamic pricing decisions on the competitor's behavior. We find that the theory is much more forgiving-in the sense that it predicts a lower level of competition among the sellers-than what we actually observe in the laboratory. The modeling literature indicates that the seller with the lower capacity has a competitive advantage, but our results reveal the opposite. Further, there is potential for high-capacity sellers to benefit from competition. Sellers tend to underprice (resp., overprice) their units at the beginning (resp., end) of a selling season. Also, competition lasts longer than the theory predicts, and customers benefit from the biases of the competing sellers. The higher-capacity seller following the best-response policy is not harmed due to the biases of the competitor. However, the lower-capacity seller's performance is greatly influenced by the competitor's degree of rationality.University of Texas at Dallas (UT Dallas) ; TÜBİTAK ; Laboratory for Behavioral Operations and Economics at the Naveen Jindal School of Managemen
Inverse radiant boundary design for ensuring desired heat treatment in vacuum batch furnaces
No full textOptimizing heat treatment processes is crucial for achieving optimal product quality within economically and environmentally effective ways. Non-uniformities in heat treatments can have detrimental effects on product quality, resulting in substantial losses in manufacturing efficiency. To optimize these heat treatment processes, this study employs nonlinear least square minimization with the Gauss-Newton algorithm to solve inverse boundary design problems. A vacuum batch furnace has been considered where the desired heat treatment is imposed at the specific locations referred to as design points within the workpiece. Two heater layouts were analyzed, and the required furnace heater temperatures have been successfully determined to achieve the desired heat treatment for both layouts. The findings highlight that ensuring uniform treatment at the design points requires nonuniform heater temperatures. Our analyses reveal that inverse solutions for heat treatment processes provide valuable tools for obtaining a range of desired treatments while highlighting the trade-offs between treatment effectiveness and practical implementation